Biochemistry and Molecular Biology and the Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, Pennsylvania, United States of America.
MSTP Program, Milton S. Hershey College of Medicine, Hershey, Pennsylvania, United States of America.
PLoS Biol. 2020 Mar 12;18(3):e3000657. doi: 10.1371/journal.pbio.3000657. eCollection 2020 Mar.
While many regulators of axon regeneration have been identified, very little is known about mechanisms that allow dendrites to regenerate after injury. Using a Drosophila model of dendrite regeneration, we performed a candidate screen of receptor tyrosine kinases (RTKs) and found a requirement for RTK-like orphan receptor (Ror). We confirmed that Ror was required for regeneration in two different neuron types using RNA interference (RNAi) and mutants. Ror was not required for axon regeneration or normal dendrite development, suggesting a specific role in dendrite regeneration. Ror can act as a Wnt coreceptor with frizzleds (fzs) in other contexts, so we tested the involvement of Wnt signaling proteins in dendrite regeneration. We found that knockdown of fz, dishevelled (dsh), Axin, and gilgamesh (gish) also reduced dendrite regeneration. Moreover, Ror was required to position dsh and Axin in dendrites. We recently found that Wnt signaling proteins, including dsh and Axin, localize microtubule nucleation machinery in dendrites. We therefore hypothesized that Ror may act by regulating microtubule nucleation at baseline and during dendrite regeneration. Consistent with this hypothesis, localization of the core nucleation protein γTubulin was reduced in Ror RNAi neurons, and this effect was strongest during dendrite regeneration. In addition, dendrite regeneration was sensitive to partial reduction of γTubulin. We conclude that Ror promotes dendrite regeneration as part of a Wnt signaling pathway that regulates dendritic microtubule nucleation.
虽然已经确定了许多轴突再生的调节剂，但对于允许树突在损伤后再生的机制知之甚少。我们使用了一个果蝇树突再生模型，对受体酪氨酸激酶（RTKs）进行了候选筛选，发现 RTK 样孤儿受体（Ror）是必需的。我们使用 RNA 干扰（RNAi）和突变体证实了 Ror 在两种不同神经元类型中的再生作用。Ror 对于轴突再生或正常树突发育不是必需的，这表明它在树突再生中具有特定的作用。Ror 在其他情况下可以与 frizzleds（fzs）作为 Wnt 共受体发挥作用，因此我们测试了 Wnt 信号蛋白在树突再生中的参与。我们发现 fz、dishevelled（dsh）、Axin 和 gilgamesh（gish）的 RNAi 也减少了树突再生。此外，Ror 对于 dsh 和 Axin 在树突中的定位是必需的。我们最近发现，包括 dsh 和 Axin 在内的 Wnt 信号蛋白在树突中定位微管成核机制。因此，我们假设 Ror 可能通过调节树突再生时的微管成核来发挥作用。与该假说一致的是，在 Ror RNAi 神经元中，核心成核蛋白γTubulin 的定位减少，并且在树突再生期间这种效应最强。此外，树突再生对γTubulin 的部分减少很敏感。我们得出结论，Ror 作为调节树突微管成核的 Wnt 信号通路的一部分，促进树突再生。
